The conventionally known superconductors are broadly divided into a copper oxide superconductor made of copper oxide and a non-copper oxide superconductor made of material other than copper oxide. Among them, the copper oxide superconductor has a higher superconducting dislocation temperature (Tc) than the non-copper oxide superconductor. However, the copper oxide superconductor has a drawback that it is hard to work because it is ceramic made of copper and oxygen and having the so-called two-dimensional surface structure. Further, on the other hand, an intermetallic compound made of only a plurality of metal elements such as MgB2 has been known as a non-copper oxide superconductor (patent document 1).
[Patent document 1] Japanese Patent Application Laid-Open No. 2002-211916
This superconductor made of MgB2 is comparatively easily formed and worked as compared with the copper oxide superconductor. However, even the intermetallic compound of MgB2 that is comparatively easily formed and worked as compared with the copper oxide superconductor has the following drawbacks: in a conventional manufacturing method of making Mg of a liquid phase react with B of a solid phase or making Mg of a gas phase react with B of a solid phase, heat treatment performed at a high temperature for a long time or a condition of high pressure is required and hence the manufacturing of the MgB2 superconductor is not practical; and in a method of using the solid phase diffusion reaction of Mg of a solid phase and B of a solid phase, the rate of formation is extremely slow.
Further, the superconductor manufactured by any one of the conventional manufacturing methods has not been always satisfactory in practical performance such as Jc characteristic and strain-resistance characteristic.
Hence, the object of the invention of this application is to provide a new method of manufacturing a MgB2 superconductor by which a superconductor, whose main component is MgB2 excellent in the above-described practical characteristics, can be manufactured easily and efficiently by heat treatment performed at or in the vicinity of a normal pressure and at a lower temperature and for a short time.